The makeshift balloon begins to lift and by the time the Daleks enter the room they find it empty. A Dalek spots them rising up the shaft. A patrol is dispatched to the surface and an anti gravitational disc summoned. Another Dalek patrol locates the explosives and sets all three bombs to detonate on timer control. After they return to the city Jo deactivates two of the bombs but is knocked out by a falling rock. The plastic sheet balloon begins to tear as the Dalek on the anti gravitational disc ascends the shaft. Waking as the bomb nears detonation Jo grabs the two deactivated bombs and flees as the remaining bomb explodes destroying the Daleks passing by on their way to the top of the ventilation shaft. The sheet tears leaving the Doctor clutching the side of the shaft. The Thals, having reached the top, lower a rope for him and when he reaches the top the throw a boulder down the shaft destroying the pursuing Dalek. The Doctor is reunited with Jo but Taron is unhappy Rebec has come Spiridon and would prefer she was safe on Skaro. The Daleks begin to prepare a bacteria to destory all living tissue: Daleks & Spiridon slaves will be innoculated but all others will be destroyed. The Doctor explains to Jo that the Daleks have their army on Spiridon. Vaber & Latep find the others and the whole group moves to the plain of stones where the boulders absorb the heat during the day and release it overnight anllowing them to keep warm. Jo goes with Latep to retrieve the explosives and befriends him. Hiding from a patrol the Doctor notices that the Daleks are slowing down and reasons that the cold might be affecting them. Codal believes destroying the refridgeration plant will destroy the Daleks. Vaber wants to attack imeadiately but Taron overules him and they struggle. The Daleks are succesfully growing their bacteria which will kill all animal life within an hour of release. The Spiridon slaves have spotted the aliens in the Plane of Stones and Daleks are sent to search it. Waking the Thals find Vaber has absconded with the explosives. Codal & Taron go to stop him leaving the others behind who spot animals aproaching. Vaber is captured by Spiridons who take him to the Daleks.

This episode calms things down a bit and finally brings the cast together, Jo & The Doctor having been separated since episode 1. We then begin the process of moving things round for the final few episodes. We get another little referance back to the past with the Daleks's anti gravitational disc, a throwback to their comics appearances in the Sixties, which get a special feature on the DVD. We also get a little glimpse in Terry Nation's current thinking as he introduces the Daleks bacterilogical weapon, a theme he'll return to in Survivors where it becomes part of the premise for the series.

I mentioned It's a Knockout! last episode in connection with the ice tunnels. Thinking about it trying to use the balloon to rise up the chimney would work as a game there too.

Liz walked in as I was watching this episode and remarked, as she does every time we see this story, that the Spiridons remind her of furry Ribena berries!

Finding themselves short of working Dalek props the BBC constructed a number of new stationary props for this story. Having made one previous appearance as a Dalek Voice (and plenty as other monsters) Roy Skelton returns to the role he's now forever linked with by Doctor Who fans, joining Michael Wisher (see Carnival of Monsters) who made his Dalek Voice debut at the end of Frontier in Space. John Scott Martin has been in every Dalek Story since the Chase and, with one exception, will be till the end of the original Doctor Who series. Murphy Grumbar's been a Dalek Operator since The Daleks and is making his penultimate appearance as a Dalek in this story. Like Michael Wisher the final Dalek Operator Cy Town made his Dalek debut in Frontier in Space and he will be in every Dalek story from now onwards.

Two important events happen between the broadcast of this episode and the next plus we pass an important milestone: we'll tell you what they are tomorrow.